Another article and interview with Shane Black that went unnoticed, posted by fAnDeB, talks about how the Avengers won't be much of a factor in IM3.

"He told the comic con audience he wants director Jon Favreau to return as Happy Hogan and added that, beyond a few references, Iron Man 3 will not involve the Avengers and will focus squarely on Tony Stark.

'We really want to make it Tony's movie,' said Black. The director also confirmed that Gwyneth Paltrow and Don Cheadle would return as Pepper Potts and Rhodey/War Machine, respectively, and that Stan Lee would have his traditional cameo."